package org.apache.lucene.search;

/**
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import org.apache.lucene.index.IndexReader;

import java.io.IOException;

/**
 * A range query that returns a constant score equal to its boost for all
 * documents in the range.
 * <p>
 * It does not have an upper bound on the number of clauses covered in the
 * range.
 * <p>
 * If an endpoint is null, it is said to be "open". Either or both endpoints may
 * be open. Open endpoints may not be exclusive (you can't select all but the
 * first or last term without explicitly specifying the term to exclude.)
 * 
 * 
 * @version $Id: ConstantScoreRangeQuery.java 564236 2007-08-09 15:21:19Z
 *          gsingers $
 */

public class ConstantScoreRangeQuery extends Query {
	private final String fieldName;
	private final String lowerVal;
	private final String upperVal;
	private final boolean includeLower;
	private final boolean includeUpper;

	public ConstantScoreRangeQuery(String fieldName, String lowerVal,
			String upperVal, boolean includeLower, boolean includeUpper) {
		// do a little bit of normalization...
		// open ended range queries should always be inclusive.
		if (lowerVal == null) {
			includeLower = true;
		} else if (includeLower && lowerVal.equals("")) {
			lowerVal = null;
		}
		if (upperVal == null) {
			includeUpper = true;
		}

		this.fieldName = fieldName.intern(); // intern it, just like terms...
		this.lowerVal = lowerVal;
		this.upperVal = upperVal;
		this.includeLower = includeLower;
		this.includeUpper = includeUpper;
	}

	/** Returns the field name for this query */
	public String getField() {
		return fieldName;
	}

	/**
	 * Returns the value of the lower endpoint of this range query, null if open
	 * ended
	 */
	public String getLowerVal() {
		return lowerVal;
	}

	/**
	 * Returns the value of the upper endpoint of this range query, null if open
	 * ended
	 */
	public String getUpperVal() {
		return upperVal;
	}

	/** Returns <code>true</code> if the lower endpoint is inclusive */
	public boolean includesLower() {
		return includeLower;
	}

	/** Returns <code>true</code> if the upper endpoint is inclusive */
	public boolean includesUpper() {
		return includeUpper;
	}

	public Query rewrite(IndexReader reader) throws IOException {
		// Map to RangeFilter semantics which are slightly different...
		RangeFilter rangeFilt = new RangeFilter(fieldName,
				lowerVal != null ? lowerVal : "", upperVal,
				lowerVal == "" ? false : includeLower, upperVal == null ? false
						: includeUpper);
		Query q = new ConstantScoreQuery(rangeFilt);
		q.setBoost(getBoost());
		return q;
	}

	/** Prints a user-readable version of this query. */
	public String toString(String field) {
		StringBuffer buffer = new StringBuffer();
		if (!getField().equals(field)) {
			buffer.append(getField());
			buffer.append(":");
		}
		buffer.append(includeLower ? '[' : '{');
		buffer.append(lowerVal != null ? lowerVal : "*");
		buffer.append(" TO ");
		buffer.append(upperVal != null ? upperVal : "*");
		buffer.append(includeUpper ? ']' : '}');
		if (getBoost() != 1.0f) {
			buffer.append("^");
			buffer.append(Float.toString(getBoost()));
		}
		return buffer.toString();
	}

	/** Returns true if <code>o</code> is equal to this. */
	public boolean equals(Object o) {
		if (this == o)
			return true;
		if (!(o instanceof ConstantScoreRangeQuery))
			return false;
		ConstantScoreRangeQuery other = (ConstantScoreRangeQuery) o;

		if (this.fieldName != other.fieldName // interned comparison
				|| this.includeLower != other.includeLower
				|| this.includeUpper != other.includeUpper) {
			return false;
		}
		if (this.lowerVal != null ? !this.lowerVal.equals(other.lowerVal)
				: other.lowerVal != null)
			return false;
		if (this.upperVal != null ? !this.upperVal.equals(other.upperVal)
				: other.upperVal != null)
			return false;
		return this.getBoost() == other.getBoost();
	}

	/** Returns a hash code value for this object. */
	public int hashCode() {
		int h = Float.floatToIntBits(getBoost()) ^ fieldName.hashCode();
		// hashCode of "" is 0, so don't use that for null...
		h ^= lowerVal != null ? lowerVal.hashCode() : 0x965a965a;
		// don't just XOR upperVal with out mixing either it or h, as it will
		// cancel
		// out lowerVal if they are equal.
		h ^= (h << 17) | (h >>> 16); // a reversible (one to one) 32 bit
										// mapping mix
		h ^= (upperVal != null ? (upperVal.hashCode()) : 0x5a695a69);
		h ^= (includeLower ? 0x665599aa : 0) ^ (includeUpper ? 0x99aa5566 : 0);
		return h;
	}
}
